Variable radius spring assembly

ABSTRACT

In combination with a knee brace, the variable radius spring assembly of the present invention provides a full range knee orthotic with support to the leg muscles without compromising the range of motion and the patient&#39;s normal walk/gate. The assembly comprises upper and lower hinge pieces attached to upper and lower sections of the brace, a spring bracket, and an elongated spring element that extends downward from the upper hinge piece past a catch on the lower hinge piece. Two such assemblies are attached to a knee brace, one on the inner side and one on the outer side. As the lower leg, and the lower hinge piece, move rearward, the catch forces the spring element rearward and slides downward along the spring element. Consequently, the spring element has a non-linear response requiring approximately the same about of force to deflect the spring element throughout its range of rearward travel.

TECHNICAL FIELD

This invention relates generally to medical devices for anatomicalsupport. This invention relates generally to knee braces. Morespecifically this invention relates to a variable radius spring assemblyfor knee braces.

BACKGROUND OF THE INVENTION

Individuals suffering from knee pain, such as from osteoarthritis, orweakened leg muscles often find some relief and support by wearing aknee brace on one or both legs. A conventional knee brace has an uppersection and lower bands or sections. The upper section has a front piecethat extends around the front of a patient's leg above the knee and isheld in place by a removable strap around the back of the leg. The lowersection also has a front piece that extends around the front of apatient's leg below the knee and is held in place by a removable straparound the back of the leg. A pair of vertical inner and outer supportsadjacent the inner and outer sides of the thigh extend downward from theupper section. A like pair of inner and outer vertical supports adjacentthe inner and outer sides of the calf extend upward from the lowersection. The two sets of vertical supports are connected to each otherwith inner and outer hinges that allow the lower section to move alongan axis relative to the upper section as the lower leg is bent, such asduring walking. The brace is able to stabilize and control motion of theknee. Some braces are used to transfer weight from a weak area of theknee to a stronger area, for example to provide some relief fromosteoarthritis.

In the applicant's experience there is a deficiency in the existing andprior art wherein many of the existing braces focus primarily onproviding lateral support to the joint rather than provide support andassistance to the leg muscles. One brace provides muscle support, butthe device uses a complicated fluid spring system that is expensive andbulky.

In the applicant's experience, there is a need for a knee brace, or adevice that can be installed on a knee brace, that will provide bothsupport and assistance to the leg muscles, allowing for a morecomfortable walking or running experience. The device of the presentinvention is believed to accomplish all of the foregoing objectives.

SUMMARY OF THE INVENTION

The present invention provides a new and useful variable radius springassembly for knee braces. This device is believed to be useful inrelieving pain or discomfort in a patient's knee(s), whether caused byosteoarthritis, surgery, or other reasons.

In one of its basic embodiments, the assembly comprises upper and lowerhinge pieces, a spring bracket, and an elongated spring element. Twosuch assemblies are attached to a knee brace, one on the inner side andone on the outer side. In an alternate embodiment only one such assemblymay be utilized. For each assembly, the upper and lower hinge pieces areattached to upper and lower sections, respectively, of a knee brace. Thespring element is secured to the spring bracket, the spring bracket issecured to the upper hinge piece, and the upper and lower hinge piecesare pivotally connected such that the lower hinge piece rotates relativeto the upper hinge piece. The spring element extends downward from thespring bracket past a catch on the lower hinge piece. When the patienton whom the knee brace is secured walks or bends his/her leg at theknee, the lower hinge piece moves rearward with the lower leg and thecatch contacts the spring element. As the lower leg, and the lower hingepiece, continue to move rearward, the catch forces the spring elementrearward and slides downward along the spring element with asubstantially constant force against the spring element. When the leg isextended, the spring element applies a substantially constant forcethroughout its travel returning to its undeflected state. Consequently,the spring element has a non-linear response and approximately the sameamount of force is required to compress the spring element throughoutits range of rearward travel while storing the same amount of energy.

When the device is in use it provides a full range knee orthotic thatprovides support to the leg muscles without compromising the range ofmotion and the patient's normal walk/gate. Furthermore, the deviceprovides lateral protection and support to the knee joint. The device isergonomic and robust enough to be worn during activities of daily lifeand most athletic endeavors.

Thus the present invention provides a new and useful variable radiusspring assembly for knee braces. The device of the present invention isbelieved to accomplish all of the foregoing objectives. Further featuresand objectives of the present invention will become apparent from thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric perspective view of a variable radius springassembly for a knee brace according to the present invention;

FIG. 2 is an exploded view of the variable radius spring assembly for aknee brace according to the present invention;

FIG. 3 is a front elevation view of the variable radius spring assemblyfor a knee brace according to the present invention;

FIG. 4 is a rear elevation view of the variable radius spring assemblyfor a knee brace according to the present invention;

FIG. 5 is a top elevation view of the variable radius spring assemblyfor a knee brace according to the present invention;

FIG. 6 is a bottom elevation view of the variable radius spring assemblyfor a knee brace according to the present invention;

FIG. 7 is a left side elevation view of the variable radius springassembly for a knee brace according to the present invention;

FIG. 8 is a right side elevation view of the variable radius springassembly for a knee brace according to the present invention;

FIG. 9 is a cross-sectional right side view of the variable radiusspring assembly for a knee brace according to the present invention; and

FIG. 10 is a isometric perspective view of an alternate embodiment ofthe present invention having a pair of variable radius spring assembliesof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a new and useful variable radius springassembly for knee braces. The following description and accompanyingdrawings disclose at least one version of the device.

Referring now to the invention in more detail in FIG. 1 to FIG. 9 thereis a variable radius spring assembly 10 shown generally for knee braces.The assembly 10 comprises an upper hinge piece 1, a spring bracket 2, alower hinge piece 3, and an elongated spring element 4. The upper hingepiece 1 comprises an upper shaft 101 and a lower cylindrical barrelhinge 100 with a central pivot bore 102 and a spring bracket receivingslot 103 along an anterior aspect of the barrel hinge 100 for receipt ofthe spring bracket 2 when assembled. The lower hinge piece 3 comprisesparallel elongated right and left plates 3A, 3B and a rear plate 3E. Theanterior aspect of the lower hinge piece 3 is angled from the middledownward and upward towards the rear. A front plate 3C covers the lowerportion of the front. The upper portion of the front, above the upperedge or catch 3D of the front plate 3C, and the top of the lower hingepiece 3 are open thereby creating a void 3F defined by the interiorgeometry of the surrounding plates 3A, 3B, 3C, 3D and retains the springelement 4 therein when the system is assembled.

The spring bracket 2 is generally prismatic in shape and comprises aslot 4A within which the spring element 4 is secured. The spring element4 is secured within the slot 4A, and extends downward towards the frontplate 2C of the lower hinge piece. When the present invention isassembled the spring element 4 extends into and moves within the void 3Fof the lower hinge piece 3. The spring bracket 2 may also be solid. Thespring element 4 may also be attached to the spring bracket 2 in otherways or may be attached directly to the upper hinge piece 1. The springbracket 2 further comprises a plurality of tabs 103 which attach to thespring bracket receiving slot 103 of the upper hinge piece 1.

A bushing, comprising an axle 5 to hold the upper hinge piece 1 and thelower hinge piece 3 together. The axle 5 extends through a right sideopening 5A near the top of the lower hinge piece right plate 3A, throughthe central pivot bore 102 of the barrel hinge 100, and through a leftside opening 5E near the top of the left plate 3B of the lower hingepiece 3. The axle is dimensioned such that, when assembled, the upperhinge piece 1, the spring bracket 2, and the lower hinge piece 3 areheld together securely while allowing the upper and lower hinge pieces1, 3 to move freely relative to each other about the axle 5. When thedevice 10 is assembled, the spring element 4 extends downward throughthe open front of the lower hinge piece 3 into the interior void 3F ofthe lower hinge piece 3.

In order to attach the variable radius spring assembly 10 of the presentinvention to a knee brace, a pair of assemblies 10 are provided. Such apair of assemblies 10 may have mirrored geometry one to the other. Oneassembly 10 attaches to the interior aspect of the knee brace medial tothe wearer's anatomy, and the other assembly 10 attaches to the exterioraspect of the knee brace radial to the anatomy. Essentially one assemblyis on either side of the wearer's knee joint within the brace. In orderto attach the assemblies 10 to the brace, a plurality of attachingpoints 200 present along each assembly 10 for the receipt of attachingmeans which can be straps, ties, snaps or stitching.

After the pair of devices 10 are attached to the knee brace, the kneebrace may be secured to the patient's leg in the usual manner. Oncesecured, the brace with the devices 10 provides support for thepatient's knee. While the following description is made in terms of asingle device 10 and its components, it will be appreciated that itapplies equally to both of the assemblies 10, which may have mirroredgeometry one to the other, attached to the knee brace.

As the patient's lower leg moves backward at the knee, the brace isrotated and the lower hinges 3 of each of the pair of assemblies 10 movebackward relative to the upper hinges 1. The upper edge 3D of the frontplate 3C of the lower hinge piece 3 contacts the spring element 4 andbegins to transfer a load. As the lower leg continues to move fartherbackward, the front plate 3C presses against the spring hinge 4, causingthe spring element 4 to deflect rearward, storing potential energy inthe spring element 4 in the form of a bending moment. Due to thekinematics involved, the point at which the load is applied, namely theupper edge catch 3D of the front plate 3 of the lower hinge, travelsfurther away (downward) from the pivoting point or lever fulcrum at theaxle 5. This effectively increases the application radius of the leversystem, allowing for greater energy storage at relatively the same forceas a standard torsion spring.

The upper and lower hinge pieces 1, 3 and the spring bracket 2 may beformed from any appropriate material, such as plastic, composite, ormetal, that has sufficient strength to withstand the forces that areplaced on them. The spring hinge 4 is preferably formed from a carbonfiber or other like material that can bend sufficiently without breakingand return to its original shape without deformation or memory overtime.

In an alternate embodiment, the present invention comprises a knee brace20 having a pair of variable radius spring assemblies 10, as illustratedin FIG. 10 . The brace 20 includes an upper frame 21 mechanicallyconnected to an upper aspect of the upper hinge piece 1 of each assembly10 and a lower frame 22 mechanically connected to a lower aspect of thelower hinge piece 3 of each assembly 10. This embodiment is attached tothe patient's anatomy by utilization of the attaching points 200 alongthe assembly 10. 17. In order to effectuate this configuration in analternative embodiment of the present invention, the assembly furthercomprises a plurality of upper frame attaching points 21A for thereceipt and attachment of an elongate upper frame 21 to the upper hingepiece 1, and a plurality of lower frame attaching points 22A for thereceipt and attachment of an elongate lower frame 22 to the lower hingepiece 3.

A standard linear spring requires more force as the angle of kneeflexion increases. When used in a knee brace, a linear spring mayprovide some support but may also encumber the normal range of motion ofthe knee and result in unwanted loadings on leg muscles. In contrastwith a standard linear spring, the varying radius spring assembly 10employed by the present invention has a non-linear response. Thus, itrequires approximately the same about of force to deflect (compress) thespring element 4 throughout its range of rearward travel while storingthe same amount of energy. This provides the same support duringextension while requiring less input on compression. When the knee isextended (substantially straight), the assembly 10 provides acounter-balancing force in the direction of extension that inhibits thebending of the knee joint. As a result, weakened leg muscles that may beunable to bear load are supported. As the spring element 4 is deflectedduring knee flexion, the pickup point, the upper edge catch 3D of thefront plate 3C of the lower hinge piece 3, extends, thereby changing theapplication radius of the moment arm at which the spring element 4 isdeflecting allowing the force against it to remain substantiallyconstant. This in turn changes the generated elastic counter force.Similarly, as the leg is extended, the spring element applies asubstantially constant force against the upper edge catch 3D of thelower hinge front plate 3C throughout its travel returning to itsundeflected state. The magnitude of the counter-balancing force from theassembly 10 can be increased or decreased by altering thecross-sectional area or material composition of the spring element 4itself.

The previously described versions of the present invention have manyadvantages including and without limitation, providing support to theleg muscles without compromising the range of motion and the patient'snormal walk/gate and providing lateral protection and support to theknee joint. The device is ergonomic and robust enough to be worn duringactivities of daily life and most athletic endeavors. The device of thepresent invention is believed to accomplish all of the foregoingobjectives. The invention does not require that all the advantageousfeatures and all the advantages need to be incorporated into everyembodiment of the invention.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. Therefore the spirit and scope of the appended claims shouldnot be limited to the description of the preferred versions containedtherein.

The reader's attention is directed to all papers and documents which arefiled concurrently with this specification and which are open to publicinspection with this specification, and the contents of all such papersand documents are incorporated herein by reference.

All the features disclosed in this specification may be replaced byalternative features serving the same, equivalent or similar purpose,unless expressly stated otherwise. Thus, unless expressly statedotherwise, each feature disclosed is one example only of a genericseries of equivalent or similar features.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered presently to be thebest mode thereof, those of ordinary skill will understand andappreciate the existence of variations, combinations, and equivalents ofthe specific embodiment, method, and examples herein. As for “means for”elements, the applicant intends to encompass within the language anystructure presently existing or developed in the future that performsthe same function. The invention should therefore not be limited by theabove described embodiment, method, and examples, but by all embodimentsand methods within the scope and spirit of the invention.

What is claimed is:
 1. A variable radius spring (VRS) assembly for aknee brace, comprising: a) an upper hinge piece having an upper shaftand a lower cylindrical barrel hinge, said barrel hinge having a centralpivot bore and a spring bracket receiving slot along an anterior aspectof the barrel hinge; b) a spring bracket having a plurality of tabswhich attach to the spring bracket receiving slot of the upper hingepiece thereby mechanically connecting the spring bracket to the upperhinge piece, said spring bracket further having a spring elementreceiving slot; c) an elongated spring element inserted into the slot ofthe spring bracket and extending downwards; d) a lower hinge piecehaving a left plate and a right plate, oriented parallel to each other,said lower hinge piece further having a rear plate, and a front platebetween and generally perpendicular to the left plate and right platethereby creating an open prismatic box with a void therein as defined bythe interior geometry of the surrounding plates, said void retaining thespring element within and allowing the free movement thereof, said lowerhinge piece attached to the upper hinge piece by an axle which passesthrough a right side opening of the right plate, the pivot bore of thecylindrical barrel hinge, and a left side opening of the left platethereby making the lower hinge piece rotatable relative to the upperhinge piece, said lower hinge piece further having a catch positioned infront of the spring element, whereby in response to the lower leg of apatient moving backward, the catch of the front plate of the lower hingepiece moves downward along the spring element, and in response to thecatch moving downward along the spring element, the spring elementdeflects rearward; and e) a plurality of attaching points along theperimeters of the upper hinge piece and the lower hinge piece, whereinsaid attaching points are fenestrations to receive an attaching meanswhich can be straps, ties, snaps or stitching.
 2. A variable radiusspring (VRS) assembly comprising: a) an upper hinge piece; b) a lowerhinge piece connected to the upper hinge piece by an axle which allowsthe lower hinge piece to rotate about an axis; and c) a spring elementattached to the upper hinge piece.
 3. The assembly of claim 2 furthercomprising a spring bracket with a slot which retains the spring elementat one end, and said spring bracket further having an attaching meansfor attaching the bracket to the upper or lower hinge piece of thepresent invention.
 4. The assembly of claim 2 wherein the upper hingepiece comprises an upper shaft and a lower cylindrical barrel hinge,said barrel hinge having a central pivot bore and a spring bracketreceiving slot along an anterior aspect of the barrel hinge.
 5. Theassembly of claim 2 wherein the lower hinge piece comprises a left plateand a right plate, oriented parallel to each other, said lower hingepiece further having a rear plate, and a front plate between andgenerally perpendicular to the left plate and right plate therebycreating an open prismatic box with a void therein as defined by theinterior geometry of the surrounding plates, said void retaining andallowing the movement of the spring element within; and said lower hingepiece further having a catch positioned in front of the spring element,whereby in response to the lower leg of the patient moving backward, thecatch of the front plate of the lower hinge piece moves downward alongthe spring element, and in response to the catch moving downward alongthe spring element, the spring element deflects rearward.
 6. Theassembly of claim 4 wherein the lower hinge piece is attached to theupper hinge piece by an axle which passes through a right side openingof the right plate, the pivot bore of the cylindrical barrel hinge, anda left side opening of the left plate thereby making the lower hingepiece rotatable relative to the upper hinge piece.
 7. The assembly ofclaim 2 further comprising a curved elongate upper frame mechanicallyconnected at one end to an upper aspect of the upper hinge piece, and acurved elongate lower frame mechanically connected at one end to a loweraspect of the lower hinge piece, said curved elongate upper framemechanically connected at an opposite end to a second assembly accordingto claim 2, wherein in the second assembly exhibits a mirrored geometry,and said curved elongate lower frame mechanically connected at anopposite end to the second assembly.
 8. The assembly of claim 2 furthercomprising a plurality of attaching points along the perimeters of theupper hinge piece and the lower hinge piece, wherein said attachingpoints are fenestrations to receive an attaching means which can bestraps, ties, snaps or stitching.
 9. A method of using the variableradius spring (VRS) assembly of claim 1, comprising: a) attaching anupper hinge piece to an upper leg portion of a patient, the upper hingepiece extending forward; b) attaching an elongated spring element to theupper hinge piece and extending downward in front of a lower leg portionof the patient; and c) attaching a lower hinge piece to the lower legportion of the patient and extending forward, the lower hinge piececomprising a catch positioned in front of the spring element whereby inresponse to the lower hinge piece moving backward, the catch of thelower hinge piece moves downward along the spring element, and inresponse to the catch moving downward along the spring element, thespring element deflects rearward.
 10. The method of claim 9 furthercomprising securing the spring element to a spring bracket which isattached to the upper hinge piece.
 11. The method of claim 9 furthercomprising securing the spring element to a spring bracket which isattached to the lower hinge piece.
 12. The method of claim 10 whereinsecuring the spring element to the spring bracket comprises securing thespring element within a slot in the spring bracket.
 13. The method ofclaim 11 wherein securing the spring element to the spring bracketcomprises securing the spring element within a slot in the springbracket.
 14. The method of claim 9, further comprising pivotallyconnecting the upper hinge piece to the lower hinge piece.
 15. Themethod of claim 9 further comprising attaching a second variable radiusspring (VRS) assembly to the other side of the patient anatomy.
 16. Themethod of claim 9 further comprising fitting the patient with a legbrace.
 17. The method of claim 16 further comprising attaching thevariable radius spring (VRS) assembly to the leg brace by an attachingmeans which can be straps, ties, snaps or stitching.
 18. The assembly ofclaim 2 further comprising a plurality of upper frame attaching pointsfor the receipt and attachment of an elongate upper frame to the upperhinge piece.
 19. The assembly of claim 2 further comprising a pluralityof lower frame attaching points for the receipt and attachment of anelongate lower frame to the lower hinge piece.